Mugen,
Well.. am always curious about the engine's lifeblood. :) To be honest.. I have this very bad habit of changing oil every 3-4K.. or when I felt the engine's startin' to get sluggish irregardless of the type of oil. High probability, due to my rich fuel mappings and my almost everyday high revvin'.. time never enough kind of job nature. Oh yeah.. forgotten to mention Selenia..quite a smooth, stable oil. ;)
For normal driving.. most oils can carry thru the 5-10K period. Yup.. Calyex is a big surprise. Smooth, powerfull and quite lasting.. especially on my ol' Wira when I had the Halvoline Energy 5W30 in it. :) Give the Semi 10w40 or fully a try. Anyway, no harm trying.